I2C schematic: 6a i2c
schematic
The I2C version with sources: 6a i2c-r09
For the I2C version two ports of the AVR have to be rewired. The
I2C schematic is also in the ZIP.

Brushed to Brushless
Conversion:

A very simple brushed to brushless conversion can
be done by using the brushed motor PWM as an input for a BLC. I
realized that methode for X-UFO conversion to brushless years ago
and actually with success for walkera 4#3 brushless conversion.
The use of a simple port-int is not recommended, better is the
use of an input capture register, like the ICP of the ATmega8
series.

The Turnigy-6A needs a little change on the PCB
to support ICP as an input. You have to exchange Pin12 and Pin32
of the ATmega8 on the board. Here is an image from TheSteve with
an example how to do it. But pay attention, you need some skills
to do it.

If you do the exchange, you can use the following
sources for the Turnigy-6A with ICP-input.